An existing device for generating electricity by friction, as shown in FIG. 1, comprises a balance weight 10, an upper electrode arranged onto the balance weight 10, and a polymeric insulating layer 20 arranged onto the upper electrode. It further comprises a lower electrode 30 opposite to the polymeric insulating layer 20, and the lower electrode 30 is connected with the balance weight 10 via an elastic support means 40. In use, due to the friction and electrostatic induction effect between the lower electrode 30 and the polymeric insulating layer 20, the device for generating electricity by friction is equivalent to a cell structure. Such device can convert mechanical energy into electric energy, which has a wide application prospect. Such device utilizes the friction between surfaces of two materials to enable one material to obtain electrons and the other one to lose electrons, thereby generating electric energy upon friction. However, the efficiency of the device for generating electricity by friction in the prior art is relatively low.